Tower 55, Modern high-rise building in downtown San Jose, California.

Tower 55 is a 15-story building at the corner of South Market Street and Post Street in downtown San Jose, completed in 1985 as the Market Post Tower. Its gold-colored glass exterior drew complaints for the light and heat it reflected. The building mixes office, telecom and retail space, and its 13th floor long housed the MAE-West Internet exchange.

The building was completed in 1985 and later became a major hub for internet connectivity. The telecommunications facility on the 13th floor served as a key data exchange center for the northern California region.

The gold glass exterior drew complaints about reflected light and heat when the building opened, and the owners put it up for sale in 1987. San Jose's first public nude sculpture stood at the Market Post Building until it was removed during the 2012 renovations. The IRS occupies a full floor as a regional office.

Tower 55 occupies the corner of South Market and Post Streets in downtown San Jose, with entrances on both streets. It is a working office, telecom and retail building: the IRS regional office holds one full floor, and CoreSite handles tenant leases. Interior floors are not open to casual visitors, so the gold glass facade is best seen from the sidewalk.

The building housed MAE-West, one of the earliest major internet exchange points that enabled data flow between different internet service providers. This role made it a critical node in the early history of commercial internet infrastructure in California.